<?php
/**
*
* This file is part of the phpBB Forum Software package.
*
* @copyright (c) phpBB Limited <https://www.phpbb.com>
* @license GNU General Public License, version 2 (GPL-2.0)
*
* For full copyright and license information, please see
* the docs/CREDITS.txt file.
*
*/

namespace phpbb\search\backend;

use phpbb\auth\auth;
use phpbb\config\config;
use phpbb\db\driver\driver_interface;
use phpbb\db\tools\tools_interface;
use phpbb\event\dispatcher_interface;
use phpbb\language\language;
use phpbb\log\log;
use phpbb\user;

/**
* Fulltext search based on the sphinx search daemon
*/
class fulltext_sphinx implements search_backend_interface
{
	protected const SPHINX_MAX_MATCHES = 20000;
	protected const SPHINX_CONNECT_RETRIES = 3;
	protected const SPHINX_CONNECT_WAIT_TIME = 300;

	/**
	 * Associative array holding index stats
	 * @var array
	 */
	protected $stats = array();

	/**
	 * Holds the words entered by user, obtained by splitting the entered query on whitespace
	 * @var array
	 */
	protected $split_words = array();

	/**
	 * Holds unique sphinx id
	 * @var string
	 */
	protected $id;

	/**
	 * Stores the names of both main and delta sphinx indexes
	 * separated by a semicolon
	 * @var string
	 */
	protected $indexes;

	/**
	 * Sphinx search client object
	 * @var \SphinxClient
	 */
	protected $sphinx;

	/**
	 * Relative path to board root
	 * @var string
	 */
	protected $phpbb_root_path;

	/**
	 * PHP Extension
	 * @var string
	 */
	protected $php_ext;

	/**
	 * Auth object
	 * @var auth
	 */
	protected $auth;

	/**
	 * Config object
	 * @var config
	 */
	protected $config;

	/**
	 * Database connection
	 * @var driver_interface
	 */
	protected $db;

	/**
	 * Database Tools object
	 * @var tools_interface
	 */
	protected $db_tools;

	/**
	 * Stores the database type if supported by sphinx
	 * @var string
	 */
	protected $dbtype;

	/**
	 * phpBB event dispatcher object
	 * @var dispatcher_interface
	 */
	protected $phpbb_dispatcher;

	/**
	 * @var language
	 */
	protected $language;

	/**
	 * @var log
	 */
	protected $log;

	/**
	 * User object
	 * @var user
	 */
	protected $user;

	/**
	 * Stores the generated content of the sphinx config file
	 * @var string
	 */
	protected $config_file_data = '';

	/**
	 * Contains tidied search query.
	 * Operators are prefixed in search query and common words excluded
	 * @var string
	 */
	protected $search_query = '';

	/**
	 * Constructor
	 * Creates a new \phpbb\search\backend\fulltext_postgres, which is used as a search backend
	 *
	 * @param auth $auth Auth object
	 * @param config $config Config object
	 * @param driver_interface $db Database object
	 * @param tools_interface $db_tools
	 * @param dispatcher_interface $phpbb_dispatcher Event dispatcher object
	 * @param language $language
	 * @param log $log
	 * @param user $user User object
	 * @param string $phpbb_root_path Relative path to phpBB root
	 * @param string $phpEx PHP file extension
	 */
	public function __construct(auth $auth, config $config, driver_interface $db, tools_interface $db_tools, dispatcher_interface $phpbb_dispatcher, language $language, log $log, user $user, string $phpbb_root_path, string $phpEx)
	{
		$this->auth = $auth;
		$this->config = $config;
		$this->db = $db;
		$this->phpbb_dispatcher = $phpbb_dispatcher;
		$this->language = $language;
		$this->log = $log;
		$this->user = $user;

		$this->phpbb_root_path = $phpbb_root_path;
		$this->php_ext = $phpEx;

		$this->db_tools = $db_tools;

		if (!$this->config['fulltext_sphinx_id'])
		{
			$this->config->set('fulltext_sphinx_id', unique_id());
		}
		$this->id = $this->config['fulltext_sphinx_id'];
		$this->indexes = 'index_phpbb_' . $this->id . '_delta;index_phpbb_' . $this->id . '_main';

		if (!class_exists('SphinxClient'))
		{
			require($this->phpbb_root_path . 'includes/sphinxapi.' . $this->php_ext);
		}

		// Initialize sphinx client
		$this->sphinx = new \SphinxClient();

		$this->sphinx->SetServer(($this->config['fulltext_sphinx_host'] ? $this->config['fulltext_sphinx_host'] : 'localhost'), ($this->config['fulltext_sphinx_port'] ? (int) $this->config['fulltext_sphinx_port'] : 9312));
	}

	/**
	 * {@inheritdoc}
	 */
	public function get_name(): string
	{
		return 'Sphinx Fulltext';
	}

	/**
	 * {@inheritdoc}
	 */
	public function is_available(): bool
	{
		return ($this->db->get_sql_layer() == 'mysqli' || $this->db->get_sql_layer() == 'postgres') && class_exists('SphinxClient');
	}

	/**
	 * {@inheritdoc}
	 */
	public function init()
	{
		if (!$this->is_available())
		{
			return $this->language->lang('FULLTEXT_SPHINX_WRONG_DATABASE');
		}

		// Move delta to main index each hour
		$this->config->set('search_gc', 3600);

		return false;
	}

	/**
	 * {@inheritdoc}
	 */
	public function get_search_query(): string
	{
		return $this->search_query;
	}

	/**
	 * {@inheritdoc}
	 */
	public function get_common_words(): array
	{
		return array();
	}

	/**
	 * {@inheritdoc}
	 */
	public function get_word_length()
	{
		return false;
	}

	/**
	 * {@inheritdoc}
	 */
	public function split_keywords(string &$keywords, string $terms): bool
	{
		// Keep quotes and new lines
		$keywords = str_replace(['&quot;', "\n"], ['"', ' '], trim($keywords));

		if ($terms == 'all')
		{
			// Replaces verbal operators OR and NOT with special characters | and -, unless appearing within quotation marks
			$match		= ['#\sor\s(?=([^"]*"[^"]*")*[^"]*$)#i', '#\snot\s(?=([^"]*"[^"]*")*[^"]*$)#i'];
			$replace	= [' | ', ' -'];

			$keywords = preg_replace($match, $replace, $keywords);
			$this->sphinx->SetMatchMode(SPH_MATCH_EXTENDED);
		}
		else
		{
			$match = ['\\', '(',')', '|', '!', '@', '~', '/', '^', '$', '=', '&amp;', '&lt;', '&gt;'];

			$keywords = str_replace($match, ' ', $keywords);
			$this->sphinx->SetMatchMode(SPH_MATCH_ANY);
		}

		if (strlen($keywords) > 0)
		{
			$this->search_query = str_replace('"', '&quot;', $keywords);
			return true;
		}

		return false;
	}

	/**
	 * {@inheritdoc}
	 */
	public function keyword_search(string $type, string $fields, string $terms, array $sort_by_sql, string $sort_key, string $sort_dir, string $sort_days, array $ex_fid_ary, string $post_visibility, int $topic_id, array $author_ary, string $author_name, array &$id_ary, int &$start, int $per_page)
	{
		// No keywords? No posts.
		if (!strlen($this->search_query) && !count($author_ary))
		{
			return false;
		}

		$id_ary = array();

		// Sorting

		if ($type == 'topics')
		{
			switch ($sort_key)
			{
				case 'a':
					$this->sphinx->SetGroupBy('topic_id', SPH_GROUPBY_ATTR, 'poster_id ' . (($sort_dir == 'a') ? 'ASC' : 'DESC'));
				break;

				case 'f':
					$this->sphinx->SetGroupBy('topic_id', SPH_GROUPBY_ATTR, 'forum_id ' . (($sort_dir == 'a') ? 'ASC' : 'DESC'));
				break;

				case 'i':

				case 's':
					$this->sphinx->SetGroupBy('topic_id', SPH_GROUPBY_ATTR, 'post_subject ' . (($sort_dir == 'a') ? 'ASC' : 'DESC'));
				break;

				case 't':

				default:
					$this->sphinx->SetGroupBy('topic_id', SPH_GROUPBY_ATTR, 'topic_last_post_time ' . (($sort_dir == 'a') ? 'ASC' : 'DESC'));
				break;
			}
		}
		else
		{
			switch ($sort_key)
			{
				case 'a':
					$this->sphinx->SetSortMode(($sort_dir == 'a') ? SPH_SORT_ATTR_ASC : SPH_SORT_ATTR_DESC, 'poster_id');
				break;

				case 'f':
					$this->sphinx->SetSortMode(($sort_dir == 'a') ? SPH_SORT_ATTR_ASC : SPH_SORT_ATTR_DESC, 'forum_id');
				break;

				case 'i':

				case 's':
					$this->sphinx->SetSortMode(($sort_dir == 'a') ? SPH_SORT_ATTR_ASC : SPH_SORT_ATTR_DESC, 'post_subject');
				break;

				case 't':

				default:
					$this->sphinx->SetSortMode(($sort_dir == 'a') ? SPH_SORT_ATTR_ASC : SPH_SORT_ATTR_DESC, 'post_time');
				break;
			}
		}

		// Most narrow filters first
		if ($topic_id)
		{
			$this->sphinx->SetFilter('topic_id', array($topic_id));
		}

		/**
		* Allow modifying the Sphinx search options
		*
		* @event core.search_sphinx_keywords_modify_options
		* @var	string	type				Searching type ('posts', 'topics')
		* @var	string	fields				Searching fields ('titleonly', 'msgonly', 'firstpost', 'all')
		* @var	string	terms				Searching terms ('all', 'any')
		* @var	int		sort_days			Time, in days, of the oldest possible post to list
		* @var	string	sort_key			The sort type used from the possible sort types
		* @var	int		topic_id			Limit the search to this topic_id only
		* @var	array	ex_fid_ary			Which forums not to search on
		* @var	string	post_visibility		Post visibility data
		* @var	array	author_ary			Array of user_id containing the users to filter the results to
		* @var	string	author_name			The username to search on
		* @var	object	sphinx				The Sphinx searchd client object
		* @since 3.1.7-RC1
		*/
		$sphinx = $this->sphinx;
		$vars = array(
			'type',
			'fields',
			'terms',
			'sort_days',
			'sort_key',
			'topic_id',
			'ex_fid_ary',
			'post_visibility',
			'author_ary',
			'author_name',
			'sphinx',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_sphinx_keywords_modify_options', compact($vars)));
		$this->sphinx = $sphinx;
		unset($sphinx);

		$search_query_prefix = '';

		switch ($fields)
		{
			case 'titleonly':
				// Only search the title
				if ($terms == 'all')
				{
					$search_query_prefix = '@title ';
				}
				// Weight for the title
				$this->sphinx->SetFieldWeights(array("title" => 5, "data" => 1));
				// 1 is first_post, 0 is not first post
				$this->sphinx->SetFilter('topic_first_post', array(1));
			break;

			case 'msgonly':
				// Only search the body
				if ($terms == 'all')
				{
					$search_query_prefix = '@data ';
				}
				// Weight for the body
				$this->sphinx->SetFieldWeights(array("title" => 1, "data" => 5));
			break;

			case 'firstpost':
				// More relative weight for the title, also search the body
				$this->sphinx->SetFieldWeights(array("title" => 5, "data" => 1));
				// 1 is first_post, 0 is not first post
				$this->sphinx->SetFilter('topic_first_post', array(1));
			break;

			default:
				// More relative weight for the title, also search the body
				$this->sphinx->SetFieldWeights(array("title" => 5, "data" => 1));
			break;
		}

		if (count($author_ary))
		{
			$this->sphinx->SetFilter('poster_id', $author_ary);
		}

		// As this is not simply possible at the moment, we limit the result to approved posts.
		// This will make it impossible for moderators to search unapproved and softdeleted posts,
		// but at least it will also cause the same for normal users.
		$this->sphinx->SetFilter('post_visibility', array(ITEM_APPROVED));

		if (count($ex_fid_ary))
		{
			// All forums that a user is allowed to access
			$fid_ary = array_unique(array_intersect(array_keys($this->auth->acl_getf('f_read', true)), array_keys($this->auth->acl_getf('f_search', true))));
			// All forums that the user wants to and can search in
			$search_forums = array_diff($fid_ary, $ex_fid_ary);

			if (count($search_forums))
			{
				$this->sphinx->SetFilter('forum_id', $search_forums);
			}
		}

		$this->sphinx->SetFilter('deleted', array(0));

		$this->sphinx->SetLimits((int) $start, (int) $per_page, max(self::SPHINX_MAX_MATCHES, (int) $start + $per_page));
		$result = $this->sphinx->Query($search_query_prefix . $this->sphinx_clean_search_string(str_replace('&quot;', '"', $this->search_query)), $this->indexes);

		// Could be connection to localhost:9312 failed (errno=111,
		// msg=Connection refused) during rotate, retry if so
		$retries = self::SPHINX_CONNECT_RETRIES;
		while (!$result && (strpos($this->sphinx->GetLastError(), "errno=111,") !== false) && $retries--)
		{
			usleep(self::SPHINX_CONNECT_WAIT_TIME);
			$result = $this->sphinx->Query($search_query_prefix . $this->sphinx_clean_search_string(str_replace('&quot;', '"', $this->search_query)), $this->indexes);
		}

		if ($this->sphinx->GetLastError())
		{
			$this->log->add('critical', $this->user->data['user_id'], $this->user->ip, 'LOG_SPHINX_ERROR', false, array($this->sphinx->GetLastError()));
			if ($this->auth->acl_get('a_'))
			{
				trigger_error($this->language->lang('SPHINX_SEARCH_FAILED', $this->sphinx->GetLastError()));
			}
			else
			{
				trigger_error($this->language->lang('SPHINX_SEARCH_FAILED_LOG'));
			}
		}

		$result_count = $result['total_found'];

		if ($result_count && $start >= $result_count)
		{
			$start = floor(($result_count - 1) / $per_page) * $per_page;

			$this->sphinx->SetLimits((int) $start, (int) $per_page, max(self::SPHINX_MAX_MATCHES, (int) $start + $per_page));
			$result = $this->sphinx->Query($search_query_prefix . $this->sphinx_clean_search_string(str_replace('&quot;', '"', $this->search_query)), $this->indexes);

			// Could be connection to localhost:9312 failed (errno=111,
			// msg=Connection refused) during rotate, retry if so
			$retries = self::SPHINX_CONNECT_RETRIES;
			while (!$result && (strpos($this->sphinx->GetLastError(), "errno=111,") !== false) && $retries--)
			{
				usleep(self::SPHINX_CONNECT_WAIT_TIME);
				$result = $this->sphinx->Query($search_query_prefix . $this->sphinx_clean_search_string(str_replace('&quot;', '"', $this->search_query)), $this->indexes);
			}
		}

		$id_ary = array();
		if (isset($result['matches']))
		{
			if ($type == 'posts')
			{
				$id_ary = array_keys($result['matches']);
			}
			else
			{
				foreach ($result['matches'] as $key => $value)
				{
					$id_ary[] = $value['attrs']['topic_id'];
				}
			}
		}
		else
		{
			return false;
		}

		$id_ary = array_slice($id_ary, 0, (int) $per_page);

		return $result_count;
	}

	/**
	 * {@inheritdoc}
	 */
	public function author_search(string $type, bool $firstpost_only, array $sort_by_sql, string $sort_key, string $sort_dir, string $sort_days, array $ex_fid_ary, string $post_visibility, int $topic_id, array $author_ary, string $author_name, array &$id_ary, int &$start, int $per_page)
	{
		$this->search_query = '';

		$this->sphinx->SetMatchMode(SPH_MATCH_FULLSCAN);
		$fields = ($firstpost_only) ? 'firstpost' : 'all';
		$terms = 'all';
		return $this->keyword_search($type, $fields, $terms, $sort_by_sql, $sort_key, $sort_dir, $sort_days, $ex_fid_ary, $post_visibility, $topic_id, $author_ary, $author_name, $id_ary, $start, $per_page);
	}

	/**
	 * {@inheritdoc}
	 */
	public function supports_phrase_search(): bool
	{
		return false;
	}

	/**
	 * {@inheritdoc}
	 */
	public function index(string $mode, int $post_id, string &$message, string &$subject, int $poster_id, int $forum_id)
	{
		/**
		* Event to modify method arguments before the Sphinx search index is updated
		*
		* @event core.search_sphinx_index_before
		* @var string	mode				Contains the post mode: edit, post, reply, quote
		* @var int		post_id				The id of the post which is modified/created
		* @var string	message				New or updated post content
		* @var string	subject				New or updated post subject
		* @var int		poster_id			Post author's user id
		* @var int		forum_id			The id of the forum in which the post is located
		* @since 3.2.3-RC1
		*/
		$vars = array(
			'mode',
			'post_id',
			'message',
			'subject',
			'poster_id',
			'forum_id',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_sphinx_index_before', compact($vars)));

		if ($mode == 'edit')
		{
			$this->sphinx->UpdateAttributes($this->indexes, array('forum_id', 'poster_id'), array((int) $post_id => array((int) $forum_id, (int) $poster_id)));
		}
		else if ($mode != 'post' && $post_id)
		{
			// Update topic_last_post_time for full topic
			$sql_array = array(
				'SELECT'	=> 'p1.post_id',
				'FROM'		=> array(
					POSTS_TABLE	=> 'p1',
				),
				'LEFT_JOIN'	=> array(array(
					'FROM'	=> array(
						POSTS_TABLE	=> 'p2'
					),
					'ON'	=> 'p1.topic_id = p2.topic_id',
				)),
				'WHERE' => 'p2.post_id = ' . ((int) $post_id),
			);

			$sql = $this->db->sql_build_query('SELECT', $sql_array);
			$result = $this->db->sql_query($sql);

			$post_updates = array();
			$post_time = time();
			while ($row = $this->db->sql_fetchrow($result))
			{
				$post_updates[(int) $row['post_id']] = array($post_time);
			}
			$this->db->sql_freeresult($result);

			if (count($post_updates))
			{
				$this->sphinx->UpdateAttributes($this->indexes, array('topic_last_post_time'), $post_updates);
			}
		}
	}

	/**
	 * {@inheritdoc}
	 */
	public function index_remove(array $post_ids, array $author_ids, array $forum_ids): void
	{
		$values = array();
		foreach ($post_ids as $post_id)
		{
			$values[$post_id] = array(1);
		}

		$this->sphinx->UpdateAttributes($this->indexes, array('deleted'), $values);
	}

	/**
	 * Nothing needs to be destroyed
	 */
	public function tidy(): void
	{
		$this->config->set('search_last_gc', time(), false);
	}

	/**
	 * {@inheritdoc}
	 */
	public function create_index(int &$post_counter = 0): array|null
	{
		if (!$this->index_created())
		{
			$table_data = array(
				'COLUMNS'	=> array(
					'counter_id'	=> array('UINT', 0),
					'max_doc_id'	=> array('UINT', 0),
				),
				'PRIMARY_KEY'	=> 'counter_id',
			);
			$this->db_tools->sql_create_table(SPHINX_TABLE, $table_data);

			$data = array(
				'counter_id'	=> '1',
				'max_doc_id'	=> '0',
			);
			$sql = 'INSERT INTO ' . SPHINX_TABLE . ' ' . $this->db->sql_build_array('INSERT', $data);
			$this->db->sql_query($sql);
		}

		return null;
	}

	/**
	 * {@inheritdoc}
	*/
	public function delete_index(int|null &$post_counter = null): array|null
	{
		if ($this->index_created())
		{
			$this->db_tools->sql_table_drop(SPHINX_TABLE);
		}

		return null;
	}

	/**
	 * {@inheritdoc}
	*/
	public function index_created($allow_new_files = true): bool
	{
		$created = false;

		if ($this->db_tools->sql_table_exists(SPHINX_TABLE))
		{
			$created = true;
		}

		return $created;
	}

	/**
	 * {@inheritdoc}
	*/
	public function index_stats()
	{
		if (empty($this->stats))
		{
			$this->get_stats();
		}

		return array(
			$this->language->lang('FULLTEXT_SPHINX_MAIN_POSTS')			=> ($this->index_created()) ? $this->stats['main_posts'] : 0,
			$this->language->lang('FULLTEXT_SPHINX_DELTA_POSTS')			=> ($this->index_created()) ? $this->stats['total_posts'] - $this->stats['main_posts'] : 0,
			$this->language->lang('FULLTEXT_MYSQL_TOTAL_POSTS')			=> ($this->index_created()) ? $this->stats['total_posts'] : 0,
		);
	}

	/**
	 * Computes the stats and store them in the $this->stats associative array
	 */
	protected function get_stats()
	{
		if ($this->index_created())
		{
			$sql = 'SELECT COUNT(post_id) as total_posts
				FROM ' . POSTS_TABLE;
			$result = $this->db->sql_query($sql);
			$this->stats['total_posts'] = (int) $this->db->sql_fetchfield('total_posts');
			$this->db->sql_freeresult($result);

			$sql = 'SELECT COUNT(p.post_id) as main_posts
				FROM ' . POSTS_TABLE . ' p, ' . SPHINX_TABLE . ' m
				WHERE p.post_id <= m.max_doc_id
					AND m.counter_id = 1';
			$result = $this->db->sql_query($sql);
			$this->stats['main_posts'] = (int) $this->db->sql_fetchfield('main_posts');
			$this->db->sql_freeresult($result);
		}
	}

	/**
	 * Cleans search query passed into Sphinx search engine, as follows:
	 * 1. Hyphenated words are replaced with keyword search for either the exact phrase with spaces
	 *    or as a single word without spaces eg search for "know-it-all" becomes ("know it all"|"knowitall*")
	 * 2. Words with apostrophes are contracted eg "it's" becomes "its"
	 * 3. <, >, " and & are decoded from HTML entities.
	 * 4. Following special characters used as search operators in Sphinx are preserved when used with correct syntax:
	 *    (a) quorum matching: "the world is a wonderful place"/3
	 *        Finds 3 of the words within the phrase. Number must be between 1 and 9.
	 *    (b) proximity search: "hello world"~10
	 *        Finds hello and world within 10 words of each other. Number can be between 1 and 99.
	 *    (c) strict word order: aaa << bbb << ccc
	 *        Finds "aaa" only where it appears before "bbb" and only where "bbb" appears before "ccc".
	 *    (d) exact match operator: if lemmatizer or stemming enabled,
	 *        search will find exact match only and ignore other grammatical forms of the same word stem.
	 *        eg. raining =cats and =dogs
	 *            will not return "raining cat and dog"
	 *        eg. ="search this exact phrase"
	 *            will not return "searched this exact phrase", "searching these exact phrases".
	 * 5. Special characters /, ~, << and = not complying with the correct syntax
	 *    and other reserved operators are escaped and searched literally.
	 *    Special characters not explicitly listed in charset_table or blend_chars in sphinx.conf
	 *    will not be indexed and keywords containing them will be ignored by Sphinx.
	 *    By default, only $, %, & and @ characters are indexed and searchable.
	 *    String transformation is in backend only and not visible to the end user
	 *    nor reflected in the results page URL or keyword highlighting.
	 *
	 * @param string	$search_string
	 * @return string
	 */
	protected function sphinx_clean_search_string($search_string)
	{
		$from = ['@', '^', '$', '!', '&lt;', '&gt;', '&quot;', '&amp;', '\''];
		$to = ['\@', '\^', '\$', '\!', '<', '>', '"', '&', ''];

		$search_string = str_replace($from, $to, $search_string);

		$search_string = strrev($search_string);
		$search_string = preg_replace(['#\/(?!"[^"]+")#', '#~(?!"[^"]+")#'], ['/\\', '~\\'], $search_string);
		$search_string = strrev($search_string);

		$match = ['#(/|\\\\/)(?![1-9](\s|$))#', '#(~|\\\\~)(?!\d{1,2}(\s|$))#', '#((?:\p{L}|\p{N})+)-((?:\p{L}|\p{N})+)(?:-((?:\p{L}|\p{N})+))?(?:-((?:\p{L}|\p{N})+))?#i', '#<<\s*$#', '#(\S\K=|=(?=\s)|=$)#'];
		$replace = ['\/', '\~', '("$1 $2 $3 $4"|$1$2$3$4*)', '\<\<', '\='];

		$search_string = preg_replace($match, $replace, $search_string);
		$search_string = preg_replace('#\s+"\|#', '"|', $search_string);

		/**
		 * OPTIONAL: Thousands separator stripped from numbers, eg search for '90,000' is queried as '90000'.
		 * By default commas are stripped from search index so that '90,000' is indexed as '90000'
		 */
		// $search_string = preg_replace('#[0-9]{1,3}\K,(?=[0-9]{3})#', '', $search_string);

		return $search_string ?: '';
	}

	/**
	 * {@inheritdoc}
	 */
	public function get_acp_options(): array
	{
		$config_vars = array(
			'fulltext_sphinx_data_path' => 'string',
			'fulltext_sphinx_host' => 'string',
			'fulltext_sphinx_port' => 'string',
			'fulltext_sphinx_indexer_mem_limit' => 'int',
		);

		$tpl = '
		<span class="error">' . $this->language->lang('FULLTEXT_SPHINX_CONFIGURE'). '</span>
		<dl>
			<dt><label for="fulltext_sphinx_data_path">' . $this->language->lang('FULLTEXT_SPHINX_DATA_PATH') . $this->language->lang('COLON') . '</label><br /><span>' . $this->language->lang('FULLTEXT_SPHINX_DATA_PATH_EXPLAIN') . '</span></dt>
			<dd><input id="fulltext_sphinx_data_path" type="text" size="40" maxlength="255" name="config[fulltext_sphinx_data_path]" value="' . $this->config['fulltext_sphinx_data_path'] . '" /></dd>
		</dl>
		<dl>
			<dt><label for="fulltext_sphinx_host">' . $this->language->lang('FULLTEXT_SPHINX_HOST') . $this->language->lang('COLON') . '</label><br /><span>' . $this->language->lang('FULLTEXT_SPHINX_HOST_EXPLAIN') . '</span></dt>
			<dd><input id="fulltext_sphinx_host" type="text" size="40" maxlength="255" name="config[fulltext_sphinx_host]" value="' . $this->config['fulltext_sphinx_host'] . '" /></dd>
		</dl>
		<dl>
			<dt><label for="fulltext_sphinx_port">' . $this->language->lang('FULLTEXT_SPHINX_PORT') . $this->language->lang('COLON') . '</label><br /><span>' . $this->language->lang('FULLTEXT_SPHINX_PORT_EXPLAIN') . '</span></dt>
			<dd><input id="fulltext_sphinx_port" type="number" min="0" max="9999999999" name="config[fulltext_sphinx_port]" value="' . $this->config['fulltext_sphinx_port'] . '" /></dd>
		</dl>
		<dl>
			<dt><label for="fulltext_sphinx_indexer_mem_limit">' . $this->language->lang('FULLTEXT_SPHINX_INDEXER_MEM_LIMIT') . $this->language->lang('COLON') . '</label><br /><span>' . $this->language->lang('FULLTEXT_SPHINX_INDEXER_MEM_LIMIT_EXPLAIN') . '</span></dt>
			<dd><input id="fulltext_sphinx_indexer_mem_limit" type="number" min="0" max="9999999999" name="config[fulltext_sphinx_indexer_mem_limit]" value="' . $this->config['fulltext_sphinx_indexer_mem_limit'] . '" /> ' . $this->language->lang('MIB') . '</dd>
		</dl>
		<dl>
			<dt><label for="fulltext_sphinx_config_file">' . $this->language->lang('FULLTEXT_SPHINX_CONFIG_FILE') . $this->language->lang('COLON') . '</label><br /><span>' . $this->language->lang('FULLTEXT_SPHINX_CONFIG_FILE_EXPLAIN') . '</span></dt>
			<dd>' . (($this->config_generate()) ? '<textarea readonly="readonly" rows="6" id="sphinx_config_data">' . htmlspecialchars($this->config_file_data, ENT_COMPAT) . '</textarea>' : $this->config_file_data) . '</dd>
		<dl>
		';

		// These are fields required in the config table
		return array(
			'tpl'		=> $tpl,
			'config'	=> $config_vars
		);
	}

	/**
	 * Generates content of sphinx.conf
	 *
	 * @return bool True if sphinx.conf content is correctly generated, false otherwise
	 */
	protected function config_generate()
	{
		// Check if Database is supported by Sphinx
		if ($this->db->get_sql_layer() == 'mysqli')
		{
			$this->dbtype = 'mysql';
		}
		else if ($this->db->get_sql_layer() == 'postgres')
		{
			$this->dbtype = 'pgsql';
		}
		else
		{
			$this->config_file_data = $this->language->lang('FULLTEXT_SPHINX_WRONG_DATABASE');
			return false;
		}

		// Check if directory paths have been filled
		if (!$this->config['fulltext_sphinx_data_path'])
		{
			$this->config_file_data = $this->language->lang('FULLTEXT_SPHINX_NO_CONFIG_DATA');
			return false;
		}

		include($this->phpbb_root_path . 'config.' . $this->php_ext);

		/* Now that we're sure everything was entered correctly,
		generate a config for the index. We use a config value
		fulltext_sphinx_id for this, as it should be unique. */
		$config_object = new \phpbb\search\backend\sphinx\config();
		/** @psalm-suppress UndefinedVariable */
		$config_data = array(
			'source source_phpbb_' . $this->id . '_main' => array(
				array('type',						$this->dbtype . ' # mysql or pgsql'),
				// This config value sql_host needs to be changed incase sphinx and sql are on different servers
				array('sql_host',					$dbhost . ' # SQL server host sphinx connects to'),
				array('sql_user',					'[dbuser]'),
				array('sql_pass',					'[dbpassword]'),
				array('sql_db',						$dbname),
				array('sql_port',					$dbport . ' # optional, default is 3306 for mysql and 5432 for pgsql'),
				array('sql_query_pre',				'SET NAMES \'utf8\''),
				array('sql_query_pre',				'UPDATE ' . SPHINX_TABLE . ' SET max_doc_id = (SELECT MAX(post_id) FROM ' . POSTS_TABLE . ') WHERE counter_id = 1'),
				array('sql_query_range',			'SELECT MIN(post_id), MAX(post_id) FROM ' . POSTS_TABLE . ''),
				array('sql_range_step',				'5000'),
				array('sql_query',					'SELECT
						p.post_id AS id,
						p.forum_id,
						p.topic_id,
						p.poster_id,
						p.post_visibility,
						CASE WHEN p.post_id = t.topic_first_post_id THEN 1 ELSE 0 END as topic_first_post,
						p.post_time,
						p.post_subject,
						p.post_subject as title,
						p.post_text as data,
						t.topic_last_post_time,
						0 as deleted
					FROM ' . POSTS_TABLE . ' p, ' . TOPICS_TABLE . ' t
					WHERE
						p.topic_id = t.topic_id
						AND p.post_id >= $start AND p.post_id <= $end'),
				array('sql_query_post',				''),
				array('sql_query_post_index',		'UPDATE ' . SPHINX_TABLE . ' SET max_doc_id = $maxid WHERE counter_id = 1'),
				array('sql_attr_uint',				'forum_id'),
				array('sql_attr_uint',				'topic_id'),
				array('sql_attr_uint',				'poster_id'),
				array('sql_attr_uint',				'post_visibility'),
				array('sql_attr_bool',				'topic_first_post'),
				array('sql_attr_bool',				'deleted'),
				array('sql_attr_timestamp',			'post_time'),
				array('sql_attr_timestamp',			'topic_last_post_time'),
				array('sql_attr_string',			'post_subject'),
			),
			'source source_phpbb_' . $this->id . '_delta : source_phpbb_' . $this->id . '_main' => array(
				array('sql_query_pre',				'SET NAMES \'utf8\''),
				array('sql_query_range',			''),
				array('sql_range_step',				''),
				array('sql_query',					'SELECT
						p.post_id AS id,
						p.forum_id,
						p.topic_id,
						p.poster_id,
						p.post_visibility,
						CASE WHEN p.post_id = t.topic_first_post_id THEN 1 ELSE 0 END as topic_first_post,
						p.post_time,
						p.post_subject,
						p.post_subject as title,
						p.post_text as data,
						t.topic_last_post_time,
						0 as deleted
					FROM ' . POSTS_TABLE . ' p, ' . TOPICS_TABLE . ' t
					WHERE
						p.topic_id = t.topic_id
						AND p.post_id >=  ( SELECT max_doc_id FROM ' . SPHINX_TABLE . ' WHERE counter_id=1 )'),
				array('sql_query_post_index',		''),
			),
			'index index_phpbb_' . $this->id . '_main' => array(
				array('path',						$this->config['fulltext_sphinx_data_path'] . 'index_phpbb_' . $this->id . '_main'),
				array('source',						'source_phpbb_' . $this->id . '_main'),
				array('docinfo',					'extern'),
				array('morphology',					'none'),
				array('stopwords',					''),
				array('wordforms',					'  # optional, specify path to wordforms file. See ./docs/sphinx_wordforms.txt for example'),
				array('exceptions',					'  # optional, specify path to exceptions file. See ./docs/sphinx_exceptions.txt for example'),
				array('min_word_len',				'2'),
				array('charset_table',				'U+FF10..U+FF19->0..9, 0..9, U+FF41..U+FF5A->a..z, U+FF21..U+FF3A->a..z, A..Z->a..z, a..z, U+0149, U+017F, U+0138, U+00DF, U+00FF, U+00C0..U+00D6->U+00E0..U+00F6, U+00E0..U+00F6, U+00D8..U+00DE->U+00F8..U+00FE, U+00F8..U+00FE, U+0100->U+0101, U+0101, U+0102->U+0103, U+0103, U+0104->U+0105, U+0105, U+0106->U+0107, U+0107, U+0108->U+0109, U+0109, U+010A->U+010B, U+010B, U+010C->U+010D, U+010D, U+010E->U+010F, U+010F, U+0110->U+0111, U+0111, U+0112->U+0113, U+0113, U+0114->U+0115, U+0115, U+0116->U+0117, U+0117, U+0118->U+0119, U+0119, U+011A->U+011B, U+011B, U+011C->U+011D, U+011D, U+011E->U+011F, U+011F, U+0130->U+0131, U+0131, U+0132->U+0133, U+0133, U+0134->U+0135, U+0135, U+0136->U+0137, U+0137, U+0139->U+013A, U+013A, U+013B->U+013C, U+013C, U+013D->U+013E, U+013E, U+013F->U+0140, U+0140, U+0141->U+0142, U+0142, U+0143->U+0144, U+0144, U+0145->U+0146, U+0146, U+0147->U+0148, U+0148, U+014A->U+014B, U+014B, U+014C->U+014D, U+014D, U+014E->U+014F, U+014F, U+0150->U+0151, U+0151, U+0152->U+0153, U+0153, U+0154->U+0155, U+0155, U+0156->U+0157, U+0157, U+0158->U+0159, U+0159, U+015A->U+015B, U+015B, U+015C->U+015D, U+015D, U+015E->U+015F, U+015F, U+0160->U+0161, U+0161, U+0162->U+0163, U+0163, U+0164->U+0165, U+0165, U+0166->U+0167, U+0167, U+0168->U+0169, U+0169, U+016A->U+016B, U+016B, U+016C->U+016D, U+016D, U+016E->U+016F, U+016F, U+0170->U+0171, U+0171, U+0172->U+0173, U+0173, U+0174->U+0175, U+0175, U+0176->U+0177, U+0177, U+0178->U+00FF, U+00FF, U+0179->U+017A, U+017A, U+017B->U+017C, U+017C, U+017D->U+017E, U+017E, U+0410..U+042F->U+0430..U+044F, U+0430..U+044F, U+4E00..U+9FFF'),
				array('ignore_chars', 				'U+0027, U+002C'),
				array('min_prefix_len',				'3 # Minimum number of characters for wildcard searches by prefix (min 1). Default is 3. If specified, set min_infix_len to 0'),
				array('min_infix_len',				'0 # Minimum number of characters for wildcard searches by infix (min 2). If specified, set min_prefix_len to 0'),
				array('html_strip',					'1'),
				array('index_exact_words',			'0 # Set to 1 to enable exact search operator. Requires wordforms or morphology'),
				array('blend_chars', 				'U+23, U+24, U+25, U+26, U+40'),
			),
			'index index_phpbb_' . $this->id . '_delta : index_phpbb_' . $this->id . '_main' => array(
				array('path',						$this->config['fulltext_sphinx_data_path'] . 'index_phpbb_' . $this->id . '_delta'),
				array('source',						'source_phpbb_' . $this->id . '_delta'),
			),
			'indexer' => array(
				array('mem_limit',					$this->config['fulltext_sphinx_indexer_mem_limit'] . 'M'),
			),
			'searchd' => array(
				array('listen'	,					($this->config['fulltext_sphinx_host'] ? $this->config['fulltext_sphinx_host'] : 'localhost') . ':' . ($this->config['fulltext_sphinx_port'] ? $this->config['fulltext_sphinx_port'] : '9312')),
				array('log',						$this->config['fulltext_sphinx_data_path'] . 'log/searchd.log'),
				array('query_log',					$this->config['fulltext_sphinx_data_path'] . 'log/sphinx-query.log'),
				array('read_timeout',				'5'),
				array('max_children',				'30'),
				array('pid_file',					$this->config['fulltext_sphinx_data_path'] . 'searchd.pid'),
				array('binlog_path',				rtrim($this->config['fulltext_sphinx_data_path'], '/\\')), // Trim trailing slash
			),
		);

		$non_unique = array('sql_query_pre' => true, 'sql_attr_uint' => true, 'sql_attr_timestamp' => true, 'sql_attr_str2ordinal' => true, 'sql_attr_bool' => true);
		$delete = array('sql_group_column' => true, 'sql_date_column' => true, 'sql_str2ordinal_column' => true);

		/**
		 * Allow adding/changing the Sphinx configuration data
		 *
		 * @event core.search_sphinx_modify_config_data
		 * @var	array	config_data	Array with the Sphinx configuration data
		 * @var	array	non_unique	Array with the Sphinx non-unique variables to delete
		 * @var	array	delete		Array with the Sphinx variables to delete
		 * @since 3.1.7-RC1
		 */
		$vars = array(
			'config_data',
			'non_unique',
			'delete',
		);
		extract($this->phpbb_dispatcher->trigger_event('core.search_sphinx_modify_config_data', compact($vars)));

		foreach ($config_data as $section_name => $section_data)
		{
			$section = $config_object->get_section_by_name($section_name);
			if (!$section)
			{
				$section = $config_object->add_section($section_name);
			}

			foreach ($delete as $key => $void)
			{
				$section->delete_variables_by_name($key);
			}

			foreach ($non_unique as $key => $void)
			{
				$section->delete_variables_by_name($key);
			}

			foreach ($section_data as $entry)
			{
				$key = $entry[0];
				$value = $entry[1];

				if (!isset($non_unique[$key]))
				{
					$variable = $section->get_variable_by_name($key);
					if (!$variable)
					{
						$section->create_variable($key, $value);
					}
					else
					{
						$variable->set_value($value);
					}
				}
				else
				{
					$section->create_variable($key, $value);
				}
			}
		}
		$this->config_file_data = $config_object->get_data();

		return true;
	}

	/**
	 * {@inheritdoc}
	 */
	public function get_type(): string
	{
		return static::class;
	}
}
